The invention relates to a gas cooking appliance with at least one radiant gas burner arranged underneath a glass ceramic cooking plate, the gas burner being leak-proof with respect to exhaust gas, with a burner plate, control devices for gas supply, ignition and safety devices, as well as monitoring devices for monitoring the temperature of the cover. The invention further relates to a process for reducing the time for heating up such gas cooking appliances.
Gas cooking appliances with radiant gas burners and glass ceramic cooking plates have been disclosed in numerous patents, for example, in U.S. Pat. No. 3,468,298, DOS 2,621,801, U.S. Pat. No. 4,083,355, and U.S. Pat. No. 4,201,184. In radiant gas burners, gas is combusted on the surface of a burner plate made of a porous ceramic material. In a gas cooking appliance, one or several such radiant gas burners are arranged at a spacing underneath a joint conventional glass ceramic plate, a cooking unit being formed by each burner on the top-side of the glass ceramic plate. Each individual radiant gas burner is provided with an ignition device and with an ignition safety device for preventing ignition of any fuel gas mixture which flows away unconsumed. A description of such a burner plate is found, for example, in EP-A 187,508.
Depending on the temperature resistance of the material, the temperature of the radiant burner plate ranges between about 900.degree. C. and 950.degree. C. The amount to be maximally fed to the burner is restricted by design features in such a way that a maximum operating temperature is not exceeded in order to protect the material of the burner plate and the cooking surface, and in order to avoid superfluous energy losses.
The permissible maximum temperature of glass ceramic cooking surfaces is usually in the range of about 700.degree. C. to 750.degree. C. Since, in case of pots having unsuitable bottoms or in case of an unoccupied cooking unit with high power being turned on, temperatures of 900.degree. C. and above can occur within a short time in the glass ceramic cooking plate, a temperature limiter is provided in order to protect the glass ceramic cooking plate. The limiter safely prevents such excess temperatures. Such temperature limiters are described in detail, for example, in DOS 2,621,801 and U.S. Pat. No. 4,201,184.
For practical use in heating a cooking surface, a regulation or control of the power of the burner must be provided in addition to limiting the temperature. Two principles are known for power control: on the one hand, the burner is operated continuously and the amount of gas supplied is reduced or increased in correspondence with the required power and, on the other hand, the burner is operated in a timed fashion, i.e., the burner is always operated with the maximum amount of gas, and the required power results from the ratio of turned on time to turned off time (cyclic ratio). Instead of a mere power control with amounts of gas or timing ratios fixedly predetermined for the individual power stages, it is also possible to provide a power regulation wherein a temperature sensor regulates the power output in dependence on the cooking unit temperature, as it is described in detail, for example, in U.S. Pat. No. 4,201,184.
Although the previous gas cooking appliances with radiant gas burners have been the subject of numerous improvements, an unresolved problem still resides in that a relatively long period of time passes between turning the burner on and the burner plate becoming red hot and thus also becoming visible, with the burner delivering full power (about 60 seconds; compare U.S. Pat. No. 4,130,104).